The present invention is related to a machine for extracting centrifuged pipe of the type including a track which is oriented substantially horizontally and which is furnished with a trough for receiving sand debris and supporting the extraction carriage, a flexible traction element for the carriage operating in two directions and including an upper part for moving the carriage in the reverse direction attached to the rear of the carriage and part for moving the carriage in the forward direction attached to a lower projection from the carriage, and means for simultaneously driving the two parts at the same speed in the two directions.
In the known machines of this general type, the transmission element is constructed of a single chain which, to depart from the rear of the carriage, extends toward the rear, runs towards the base on a motor chain wheel, extends towards the front portion to a fixed chain wheel and finally returns to the rear at the projection. This chain is entirely continuous in the vertical plane of symmetry of the machine and, necessarily, a part of the chain extends above the trough and is directly exposed to the sand debris which results in the breaking of the chain or its joining members frequently during the extraction operation. The debris rapidly wears out the chain and the chain wheels and also hinders lubrication of the chain.
An object of the invention is to provide an extracting machine which does not have this problem and which, consequently, can function for long periods of time without replacement of the carriage driving mechanism.
To achieve this, the invention has as an object a machine of the above described type characterized in that the trough includes lateral edges and in that the lower part includes two halves which are each attached to a lateral elbow bracket projecting under the carriage and which extend under the edges. Thus, the lower part of the traction element is protected from sand debris.
This protection is further enhanced in that the supporting structure for the track has at each side a basin or cavity in which the two halves are positioned and of which the lateral wall extends upward to the vicinity of the corresponding bracket.
The falling sand may further be completely isolated from one part of the traction element if the upper part is situated in the assembly in the plane of symmetry of the carriage, is separated from the lower part and is rolled around a motor drum situated beyond the end of the rear part of the track. In this case, the mechanical assembly of the invention can have a particularly simple and reliable structure if each half of the lower part includes two portions, one of which is wrapped around an end of the motor drum.
The inventive concept is particularly well adapted for using cables for the flexible elements which thereby makes the machine much quieter than prior art constructions.
Still further, it is quite advantageous that, in a machine of the type mentioned above, the driving means includes a two-speed motor, for example, a constant power hydraulic motor with variable cylinders controlled by a distributor. In effect, the motor power available is then perfectly well adapted to the requirements of extracting the centrifuged pipe which requires the provision of a main force and a slow displacement of the carriage to detach the pipe from the shell, after which a much more weak force but a much more rapid displacement is necessary to increase the rate of production and to derive the maximum benefit from the heat energy stored in the casting furnace, as well as to reduce the subjection of the shell to excessive thermal constraints, thereby risking its deformation.